Field of the Invention
The present disclosure relates to a technology for detecting a touch input by an operator.
Description of the Related Art
In recent years, there has been a circumstance in which a user interface (hereinafter, will be referred to as a UI) is projected onto an arbitrary surface such as a wall or a desk, and a touch is performed on the projected UI. In addition, there has been a circumstance in which a touch is performed on a physically existing object, and information related to the object is displayed on a head mount display (HMD) on the basis of the touch in an environment such as an augmented reality (AR) or a mixed reality (MR).
In the above-described circumstances, it is determined in many times whether or not a target surface and a part of a predetermined object (for example, a fingertip of an operator) are in contact with each other on the basis of a distance between the target surface and the part of the predetermined object by using an imaging unit for a range image which can obtain distance information such as a stereo camera or an infrared camera. Specifically, a predetermined threshold is set with respect to the distance between the target surface and the fingertip of the operator, and it is determined that the fingertip touches the target surface in a case where the target surface and the fingertip come close to each other to such an extent that the distance becomes lower than the threshold. Hereinafter, a contact made from a state in which the fingertip and the target surface are not in contact with each other will be referred to as a touch, and a non-contact state made from the contact state will be referred to as a release.
In the touch detection based on the range image, the target surface may be shielded by the predetermined object, which may become a dead corner for a unit configured to obtain the distance information such as the imaging unit for the range image. Therefore, even in a case where the target surface is shielded by the predetermined object, it is necessary to estimate a distance from the imaging unit to the target surface.
According to Japanese Patent NO. 4858631, a predetermined image is projected onto the target surface, and an image capturing the target surface on which the predetermined image is projected is analyzed, so that the distance from the imaging unit to the target surface is measured in advance.
In a case where the object including the target surface moves, a case where the imaging unit mounted to the HMD moves, or the like, the distance from the imaging unit to the target surface may vary in some cases. It is sufficient when a distance relationship between the target surface and the imaging unit after the distance variation can be measured again, but in a case where the distance variation occurs in a state in which the target surface is shielded by the predetermined object, it is difficult to measure the distance between the imaging unit and the shielded area again. No considerations have been made with respect to the above-described case in Japanese Patent No. 4858631, and the touch operation with respect to the target surface that varies in the shielded state is not detected.